Back when there were only six commercial TV channels in New York, certain shows held a greater impact than they reasonably should have.

Example: “My Three Sons,” a father-knows-best number — Fred MacMurray the calm, sagacious, pipe-smoking, blueprints-in-a-cylinder-carrying dad — that began in 1960 on ABC and ended on CBS, 12 years and 300 episodes later.

Put it this way: Throughout the 1960s, I didn’t know one kid actually named Ernie, but I knew half-a-dozen called Ernie. Any scrawny kid who wore a toothy smile and a pair of glasses was called Ernie, corresponding to that character on “My Three Sons.”

When I went to college in Southwestern, Pa., I met two more “Ernies,” one whose real name was Tom — 40 years later, he’s still called Ernie — the other whose real name I never knew.

Late last month, Don Grady — who played Rob Douglas, the middle brother who became the eldest brother when Mike, played by “Mickey Mouse Club” and “Spin and Marty” grad Tim Considine, left “My Three Sons” — died of cancer, at 68.

News of his death resurrected for me some childhood, TV-driven issues that still haven’t been reconciled.

It was about Ernie. When Ernie, played by Barry Livingston, first showed up, he was a neighborhood kid, who’d alternately pester and charm the Douglas household. I don’t recall ever seeing Ernie’s parents or even being given a glimpse of his house.

And then one day Ernie just moved in with the Douglas family and became the new third son. Did Ernie’s folks no longer want him? Had he worn out his welcome at their house? Could this happen to me if I didn’t, as my dad would strongly suggest, “toe the line” (whatever that meant)?

The brief cover story was that Ernie’s dad was transferred to the Far East; so his parents just dropped him off at the Douglas house and never — not for years, not ever — returned, not so much as a letter or a Christmas card.

Were they in the Far East or in Eastern State Penitentiary?

And Ernie became Ernie Douglas, and that was that. Geez.

Years later when my daughters watched “Sesame Street,” it included a song to reassure 4- and 5-year-olds that being left with a baby sitter or at day care was no big deal, that your parents will return.

It went something like, “They are coming back; they are coming back; they never will forget you!”

And when I listened as that was sung to my kids, all I could think of was Ernie Douglas. “They don’t always come back,” I’d grumble to myself.

I guess it’s time to let go. If only I could.

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The perfect marriage of sleaze to sleaze will occur this month when Charlie Sheen joins Vince McMahon’s WWE in a USA Network episode of kid-reliant “Raw.”

Trump, who once lectured a disgraced, drug-busted Miss USA — he owns the pageant — on the dangers of drug use, has appeared five times on McMahon’s shows. Yet, he seems blind to the staggering number of job-related drug-deaths of pro wrestlers in the last 35 years.

It all goes round and round, and it comes out a twisted mess. This year, presidential candidates Mitt Romney and Newt Gingrich each sought the public approval of the attention-starved Trump, while Sheen’s blatantly anti-Semitic attack on “Two and a Half Men” creator Chuck Lorre has, for the sake of business, been conveniently forgotten.

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Now Hear This (correctly): I committed a flagrant foul here, last Sunday, when I wrote that NY1 had promoted the continued “celebration of Crime Week.” In fact, the celebration was of Pride Week. Bad one.